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International audience; Protecting crops against pests is a major issue in the current agricultural production system. In particular,assessing the risk to crops can promote integrated pest management (IPM) strategies that encourage naturalcontrol mechanisms and advocate the use of pesticides as a last resort. In this study, we focused on wireworms,major soil-dwelling insect pests inflicting severe economic damage on various crops (including maize, potatoesand cereals) across Europe and North America. We have developed an original hierarchical Bayesian model thatexplicitly accounts for biological knowledge and uncertainty in field observations, rather than relying solely onstatistical correlations, to predict the level of wireworm infestation. The model was calibrated and validatedusing a substantial dataset originating from an agro-environmental survey carried out over three consecutiveyears (2012–2014) in France, which provides the wireworm abundance in 419 maize fields, together with informationon the landscape context, field history, weather conditions, soil characteristics and farming practicesassociated to each field. Model outcomes show good agreement with current knowledge from literature and fieldexpertise in terms of the effects of variables on wireworm abundance, and provide fairly good predictive capacity.Subsequently, the model was encapsulated as a software (R shiny application) to predict the risk ofwireworm infestation in any field of interest, and can be used by farmers or agricultural advisors as a decisionsupport system for the implementation of IPM strategies. The conceptual framework that we implemented can beadapted to a wide range of similar situations involving other crops and pests.

Pests and diseases greatly contribute to the decline in banana yields, food and income insecurity in the Great Lakes region of Africa. Understanding people’s role in pest and disease spread at landscape level is crucial for effective pest and disease management. To determine this, focus group discussions (FGDs) targeting 10 experienced farmers (50% female and 50% male) were conducted in 27 villages along four banana trade routes in western Burundi and eastern DR Congo. FGDs determined the presence and risk of spread of key banana pests and diseases via the movement of banana bunches, planting material and other products, labourers, traders and farm tools. Black leaf streak (BLS), Fusarium wilt and banana bunchy top disease (BBTD) were reported to have been in the landscape for over 40 years while Xanthomonas wilt (XW) was a more recent introduction (1-7 years). BBTD, XW and weevils were the most prevalent constraints. BBTD was observed at previously unsuitable high-altitude zones, which should be a cause of concern, especially with the current risk of climate change. Climate change, and linked temperature increases, could also worsen the prevalence of XW, weevils, nematodes and BLS. Movement of farming tools by labourers and traders, of planting material/suckers and banana bunches emerged as the most common human practices potentially responsible for the spread and/or build-up of banana pests/diseases. Strengthening farmer’s knowledge and institutional capacities of actors on these different modes of disease spread in banana value chains in the region is recommended. Key words: Black leaf streak, bunchy top disease, Fusarium wilt, nematodes, weevils, Xanthomonas wilt.

The serious damages of Xylella fastidiosa (Xf) in Euro-Mediterranean countries (e.g. Italy, France, Spain) raise concerns for the Near East and North Africa (NENA). Therefore, a study was performed to a) assess the risk of Xf entry, establishment and spread in target NENA countries (viz. Algeria, Egypt, Jordan, Lebanon, Libya, Morocco, Palestine, Syria, Tunisia); b) analyze risk perception and preparedness level among agri-food chain stakeholders; c) estimate potential socio-economic impacts for olives, grapes and citrus. Pest risk appraisal suggests that Morocco, Lebanon, Palestine and Syria are the most exposed to Xf risk; other target NENA countries, except Algeria, have an intermediate risk. Risk perception analysis shows that governance efficacy and practices application can be improved by involving stakeholders and raising their awareness. Socio-economic impact assessment indicates declining yields, production, profitability, export, employment, and increasing import, with the highest impacts relating to olives, then citrus and grapes. The study suggests that the expected socio-economic impacts are unacceptable and require urgent action against Xf at national and regional levels.

Significance Xylella fastidiosa is one of the most dangerous plant-pathogenic bacteria worldwide. Regulatory measures were enacted in response to the detection of the subsp. pauca (Xfp) in Italian olives in 2013, but the current impact is nevertheless major. We developed a spatially explicit bio-economic model to compute potential future economic impact of the Xfp strain. Uncertainty on spread is accounted for by simulating different scenarios. The majority of orchards were found to be within climatically suitable territory. Even under slow disease spread and the ability to replant with resistant cultivars, projections of future economic impact in affected countries run in the billions of Euros. Our findings highlight the importance of minimizing disease spread and implementing adaptation measures in affected areas., Xylella fastidiosa is the causal agent of plant diseases that cause massive economic damage. In 2013, a strain of the bacterium was, for the first time, detected in the European territory (Italy), causing the Olive Quick Decline Syndrome. We simulate future spread of the disease based on climatic-suitability modeling and radial expansion of the invaded territory. An economic model is developed to compute impact based on discounted foregone profits and losses in investment. The model projects impact for Italy, Greece, and Spain, as these countries account for around 95% of the European olive oil production. Climatic suitability modeling indicates that, depending on the suitability threshold, 95.5 to 98.9%, 99.2 to 99.8%, and 84.6 to 99.1% of the national areas of production fall into suitable territory in Italy, Greece, and Spain, respectively. For Italy, across the considered rates of radial range expansion the potential economic impact over 50 y ranges from 1.9 billion to 5.2 billion Euros for the economic worst-case scenario, in which production ceases after orchards die off. If replanting with resistant varieties is feasible, the impact ranges from 0.6 billion to 1.6 billion Euros. Depending on whether replanting is feasible, between 0.5 billion and 1.3 billion Euros can be saved over the course of 50 y if disease spread is reduced from 5.18 to 1.1 km per year. The analysis stresses the necessity to strengthen the ongoing research on cultivar resistance traits and application of phytosanitary measures, including vector control and inoculum suppression, by removing host plants.

Pest Risk Analysis (PRA) is the process of evaluation for biological and economic evidences in order to determine whether a pest should be regulated under phyto-sanitary measures. The present mini review highlights the potential potato pathogen list recorded in Nepal harmful for potato production and productivity. At global scale altogether 135 potential quarantine pests (PQP) for potato has been recorded, while in Nepal only 92 PQP were recorded. Out of those 52, 13 and 27 were fungi, bacteria and viruses respectively. Among the 92 PQP, 34, 30 and 13 were considered at high, medium and lower risk type pathogens for potato. There was no information available on other 15 PQP.Journal of Nepal Agricultural Research Council Vol.3 2017: 32-37

International audience; The international seed trade is considered relatively safe from a phytosanitary point of view and is therefore less regulated than trade in other plants for planting. However, the pests carried by traded seeds are not well known. We assessed insects and fungi in 58 traded seed lots of 11 gymnosperm and angiosperm tree species from North America, Europe, and Asia. Insects were detected by X-raying and molecular methods. The fungal community was characterized using high-throughput sequencing (HTS) and by growing fungi on non-selective agar. About 30% of the seed lots contained insect larvae. Gymnosperms contained mostly hymenopteran (Megastigmus spp.) and dipteran (Cecidomyiidae) larvae, while angiosperms contained lepidopteran (Cydia latiferreana) and coleopteran (Curculio spp.) larvae. HTS indicated the presence of fungi in all seed lots and fungi grew on non-selective agar from 96% of the seed lots. Fungal abundance and diversity were much higher than insect diversity and abundance, especially in angiosperm seeds. Almost 50% of all fungal exact sequence variants (ESVs) found in angiosperms were potential pathogens, in comparison with around 30% of potentially pathogenic ESVs found in gymnosperms. The results of this study indicate that seeds may pose a greater risk of pest introduction than previously believed or accounted for. A rapid risk assessment suggests that only a small number of species identified in this study is of phytosanitary concern. However, more research is needed to enable better risk assessment, especially to increase knowledge about the potential for transmission of fungi to seedlings and the host range and impact of identified species.

Following a series of requests for scientific advice from the European Commission starting in 2013, the European Food Safety Authority (EFSA) conducted a pest risk assessment and created a comprehensive Xylella fastidiosa host plant database. The last update of the database, published in September 2018, includes information on host plants of both X. fastidiosa and X. taiwanensis, together with details on botanical classification, infection conditions, geographic location, pathogen taxonomy including information on subspecies, strain and sequence type, detection techniques, and tolerant/resistant response of the plant. This updated database of host plants of Xylella spp. reported worldwide provides a key tool for risk management, risk assessment, and research on this generalist bacterial plant pathogen.

In 2006, US Department of Agriculture Animal and Plant Health Inspection Service published a landmark rule providing generic radiation quarantine treatments. The rule approved radiation doses of 150 Gy for any tephritid fruit fly and 400 Gy for all other insects except the pupa and adult stages of Lepidoptera. The generic radiation treatments apply to all fresh horticultural commodities. Therefore, if a pest risk assessment demonstrates that no pupae or adult Lepidoptera are associated with a commodity, export approval can be forthcoming with no further research. Generic treatments are the culmination of decades of research but not an end point. Future research on quarantine and phytosanitary uses of radiation should focus on (1) development of specific doses for quarantine Lepidoptera not covered by the generic treatments, (2) reduction of dose levels for specific pests and commodities to shorten treatment time and minimize any deleterious effects of radiation treatment on commodity quality, (3) development of generic doses below 400 Gy for important groups of quarantine arthropods other than fruit flies, and (4) development of information on commodity tolerance and development of value-added irradiated fresh products using generic radiation treatments. Generic treatments will facilitate safe trade between countries that have approved phytosanitary uses of radiation for fresh agricultural commodities.

Pest risk assessment studies are aimed at evaluating if weather conditions are suitable for the potential entry and establishment of an organism in a new environment. For fungal plant pathogens, the crucial aspect to be explored is the fulfillment of the infection process, that constitutes the first phase of the development of an epidemic as mainly driven by temperature and leaf wetness duration. This is of particular interest for climate change studies, because the modified pattern of temperature and moisture regimes could completely alter the known distribution and severity of plant disease epidemics. Biophysical process-based models could effectively be used in such studies, because they allow, within their applicability range, estimating organisms responses to climatic drivers in environmental conditions not yet experienced. One of the prerequisite of their adoption in operational contexts is a sensitivity analysis assessment aimed at understanding their ability (i) to differentiate the responses according to different parameterizations and (ii) to be sensitive to the variability of the input data. In this study, a generic potential fungal infection model simulating four pathogens chosen to provide a wide range in temperature and moisture requirements was analyzed. The model was run under diverse climatic conditions. The sensitivity of the model significantly changed according to the pathogen tested, and the relevance of its parameters in explaining model output resulted strongly linked to the environmental conditions tested, indicating its to be used in pest risk assessment studies.

Epitrix tuberis and E. cucumeris are major pests of potatoes in North America. E. tuberis causes the most serious damage because the larval feeding can cause superficial serpentine tunnelling on the surface of tubers as well as deeper pits. This damage can make crops unmarketable. By contrast, E. cucumeris mainly damages the foliage, and yield losses can occur when the adults reach high densities. In 2004, potato tuber damage characteristic of E. tuberis was seen in Portugal. In 2008, damage was more widespread and severe. E. cucumeris and a lesser known species, E. similaris, were recorded in affected fields. E. similaris has since been found across Galicia, Spain. E. similaris is thought to be the most likely cause of the tuber damage in Portugal, but it is possible that E. cucumeris or an as yet undetected Epitrix species is causing the damage. In 2010, a pest risk assessment for the Euro-Mediterranean area identified the movement of adults and pupae with seed or ware potatoes and associated soil as being the highest-risk pathways for the spread of Epitrix. In 2012, EU emergency measures were agreed to reduce the risk of further introductions and the rate of spread of these pests.

Liriomyza huidobrensis (Blanchard) is an economically important and highly polyphagous worldwide pest. To establish a temperature-dependent phenology model, essential for understanding the development and growth of the pest population under a variety of climates and as part of a pest risk analysis, L. huidobrensis life-table data were collected under laboratory conditions at seven constant temperatures on its host faba bean (Vicia faba L.). Several nonlinear equations were fitted to each life stage to model the temperature-dependent population growth and species life history and finally compile an overall temperature-dependent pest phenology model using the Insect Life Cycle Modeling (ILCYM) software. Liriomyza huidobrensis completed development from egg to adult in all temperatures evaluated, except at 32 °C, which was lethal to pupae. Eggs did not develop at 35 °C. Mean development time of all immature stages decreased with increasing temperature. Nonlinear models predicted optimal temperature for immature survival between 20–25 °C (32–38% mortality of all immature stages). Life-table parameters simulated at constant temperatures indicated that L. huidobrensis develops within the range of 12–28 °C. Simulated life-table for predicting the population dynamics of L. huidobrensis under two contrasting environments showed that lowland temperatures at the coast of Peru (250 m.a.s.l.) presented better conditions for a potential population increase than highland (3,400 m.a.s.l.) conditions. The presented model linked with Geographic Information Systems will allow pest risk assessments in different environmental regions to support the regulation of pest movement to prevent pest entry into not-yet invaded regions as well as to implement effective management strategies.

The risk of introducing weeds to new areas through grain (cereals, oilseeds and pulses) intended for processing or consumption is typically considered less than that from seed or plants for planting. However, within the range of end uses for grain, weed risk varies significantly and should not be ignored. In this paper, we discuss pathway risk analysis as a framework to examine the association of weed seeds with grain commodities throughout the production process from field to final end use, and present inspection sampling data for grain crops commonly imported to Canada. In the field, weed seed contamination of grain crops is affected by factors such as country of origin, climate, biogeography and production and harvesting practices. As it moves toward export, grain is typically cleaned at a series of elevators and the effectiveness and degree of cleaning are influenced by grain size, shape and density as well as by grade requirements. In cases where different grain lots are blended, uncertainty may be introduced with respect to the species and numbers of weed seed contaminants. During transport and storage, accidental spills and cross-contamination among conveyances may occur. At the point of import to Canada, inspection sampling data show that grain shipments contain a variety of contaminants including seeds of regulated weeds and species that represent new introductions. However, grain cleaning and processing methods tailored to end use at destination also affect the presence and viability of weed seeds. For example, grains that are milled or crushed for human use present a lower risk of introducing weed seeds to new environments than grains that undergo minimal or no processing for livestock feed, or screenings that are produced as a by-product of grain cleaning. Pathway risk analysis allows each of these stages to be evaluated in order to characterize the overall risk of introducing weeds with particular commodities, and guide regulatory decisions about trade and plant health.

The application of pest risk analysis (PRA) decision-support schemes, such as that used by the European and Mediterranean Plant Protection Organization (EPPO), generates many ratings for likelihood or magnitude of risk factors, each with an associated uncertainty. In accordance with the international standard ISPM 11 (FAO, 2004), questions have been devised to assess the key elements of pest risk in the four main sections of pest risk assessment: Entry, Establishment, Spread and Impact. After completing each section, risk assessors are required to give a summary rating and an uncertainty score for that section. The large number of question ratings and uncertainty scores make the task of summarizing each section and its uncertainty quite difficult. Two graphical tools have been developed to aid this task: the PRA Risk score and uncertainty visualizer (Visualizer) and the Rule-based matrix model (RBMM). The Visualizer presents a case summary graph on a single page in such a way that the risk assessors and peer reviewers can see rating scores and uncertainties in a pictorial manner; the RBMM integrates all the individual questions in the assessment through a hierarchy of rules that attempt to mimic the logic used by the assessors and are arranged in the form of a flow chart to give an overall rating with an accompanying expression of uncertainty.

The paper presents a model for quantifying quarantine-related phytosanitary measures by combining the two basic components of pest risk assessment—probability of establishment and economic effects—into a single management framework, iso-risk. The model provides a systematic and objective basis for defining and measuring acceptable risk and for justifying quarantine actions relative to acceptable risk. This can then be used to measure consistency of phytosanitary measures. The iso-risk framework is applied to APHIS-USDA phytosanitary risk assessments using a database of qualitative risk assessments and phytosanitary requirements for different agricultural and horticultural commodities. The results show that the APHIS-USDA risk assessment system produces assessments that are not consistent across a range of intermediate values for consequence or likelihood of occurrence.

Host area, potential pest impact and probability of pest presence are frequently displayed on maps by pest risk assessors. These variables can be mapped separately, but it is also important to map combinations of these variables in order to define the area of potential establishment and the endangered area to assist decision-making processes. This paper presents different methods for combining maps, and discusses their advantages and disadvantages. Different methods are shown that can be used to combine maps depending on whether the individual maps were derived from continuous quantitative variables or from discrete variables. The authors suggest combining maps derived from continuous variables using simple mathematical equations in order to compute expected invaded areas and expected potential impacts. Maps derived from discrete variables (e.g. scores) can be combined using a risk matrix, but the results may be highly dependent on the chosen matrix. The practical interest of these methods is illustrated in a case study on Diabrotica virgifera virgifera. The authors recommend combining the original continuous variables when such variables are available. The combination of categories defined from continuous variables led to a loss of information and may decrease the values of the maps. Risk matrices should be used only if the individual variables are discrete and if the underlying continuous variables are not available.

The phytosanitary risk associated with the movement of export-quality apple fruit to countries where fire blight does not occur is reassessed based upon additional data available since 1998 and clarification or correction of previously misinterpreted data present in the literature. The low epiphytic fitness of Erwinia amylovora (Ea) on apple fruit, the documented low incidence of viable Ea populations on mature apple fruit and the lack of a documented pathway by which susceptible host material could become infected from fruit-borne inoculum remain unchanged, and support the view that movement of Ea via commercial apple fruit is highly unlikely. With this new information, we updated a previously published model to re-estimate the likelihood of fire blight outbreaks in new areas because of commercial fruit shipment. This likelihood decreased in every scenario, and ranged from one outbreak in 5217 years to one in 753,144 years. By using the corrected and newly published data and by making assumptions based upon documented pathogen biology, the model gives more robust statistical support to the opinion that the risk of importing Ea on commercial apple fruit and the concomitant risk of establishing new outbreaks of fire blight is so small as to be insignificant.

The estimation of rates and patterns of spread is one of the key steps in a pest risk assessment. Pest risk analysts across the world wish to make quantitative, scientifically defensible assessments of likely spread by invasive alien species. However, data and time to develop detailed models for pest invasions are usually lacking and the resources to test those models in practice are not available. Therefore, generic and simple models are needed. A generic spread module composed of four models has been developed to assess the spread of plant pests. Four different models were developed to represent differences in objectives, available data and assumptions underlying the assessment of spread. The most complex of the models simulates spread in time and space and has four biological parameters, representing population growth and dispersal. The simplest of the models has only one parameter and considers only geographic range expansion. A third model assumes logistic growth of invaded area and a fourth model assumes logistic growth of population density in invaded cells. All models consider climatic suitability and presence of hosts. Consideration of economic value is optional. This chapter describes concepts and application of these models. They are illustrated by case studies for western corn rootworm, Diabrotica virgifera virgifera, in Europe.

The invasion risk posed by the xylem feeding hemipteran, Homalodisca coagulata (native to the southeast USA and northeast Mexico, and a recent invader of California (USA) and Tahiti) and a xylem-dwelling phytopathogenic bacterium, Xylella fastidiosa (native to the Americas and causative agent of Pierce's disease of grape vines), was examined using the computer climate modeling program CLIMEX. Model predictions indicated that suitable climatic conditions for H. coagulata and Pierce's disease causing strains of X. fastidiosa exist in almost all grape production areas of the world, and H. coagulata may be able to colonize areas unsuitable for X. fastidiosa. Additionally, the model indicated that regions north of California will be unable to sustain populations of both pests because of cold stress, and that irrigation of agricultural and urban areas in California's deserts has removed dry stress limitations, which when combined with a depauperate natural enemy fauna most likely facilitated successful invasion by H. coagulata. CLIMEX predicted that cold stress accumulation would exclude Pierce's disease causing strains of X. fastidiosa from France and northern and central grape producing areas of Spain and Italy. This result is incongruous with Pierce's disease reports from Kosovo in the Balkans and may suggest that cold-tolerant strains of X. fastidiosa that cause Pierce's disease exist which could exhibit invasion potential and establish in areas of Europe contrary to results reported here.

The EPPO pest risk assessment scheme requires scores on a 1-9 scale to be assigned to 48 questions covering the potential for entry, establishment and impacts in a defined area. In this paper, we explore the extent to which the choice of scores can be assisted by providing descriptions for each number on the 1-9 scale. Such assistance would not only simplify the task faced by risk assessors, but also serve to standardize responses, thus enhancing the ability to compare the risks posed by different pests. We conclude that it is possible to provide descriptions for each score on the 1-9 scale for questions where assessments can be based on a numerical value. For questions which can only be answered with an expert opinion in the form of words, such as low, medium or high, only general guidance can be given.

Four main characters are associated with the potential of Lymantria dispar for international spread in ships moving from the Russian Far East to other Pacific countries: movement to light, wind dispersal of young larvae, length of egg stage, host range of larvae. Other Far Eastern lymantriid species have been scored for these characters on a 1-5 scale to provide an estimate of the risk of such international spread. Lymantria spp. score highest on this scale, and a few other lymantriids have scores indicating that there is a definite risk. Most of the species scored cannot, however, be adequately assessed for all the characters because of lack of information, indicating the need for further research before an adequate pest risk assessment can be done.

Increasing world trade in unmanufactured wood articles has amplified the risks of inadvertent introduction of pests into new environments. Previous introductions of non-native invasive organisms into the United States have resulted in severe outbreaks with economic and ecological disruption in forests. The United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) and the USDA Forest Service have developed a pest risk assessment process that attempts to identify the risks associated with importation of unmanufactured wood articles. Assessments have been completed for importation into the United States of logs from Russia, New Zealand, Mexico, and South America. The results of these assessments are considered in developing regulatory approaches to preventing introductions of non-native invasive organisms.

The Panel on Plant Health assessed the risk to plant health from Phytophthora fragariae for the European Union and evaluated the current EU legislation and possible risk reduction options. The pest is present in most areas of Europe except southern Mediterranean regions. Entry through the plants for planting, but not seeds, pathway, is assessed as a major pathway, with the probability of entry rated as unlikely and the uncertainty as high. The probability of establishment is likely in the absence of existing disease control practices with low uncertainty. The probability of spread in the absence of a scheme for the production of certified plants for planting is considered to be very likely. With certification, spread is considered to be unlikely to moderately likely, depending on the inclusion of testing for the pathogen as part of certification. These ratings have medium uncertainty. Potential impact is rated as minor with medium uncertainty. The Panel evaluated the effectiveness of current EU legislation regarding the introduction and spread of P. fragariae. According to the regulation the import of Fragaria plants for planting, other than seeds, is prohibited from specified countries, whereas for import of these plants from other countries and for movement of these plants within the EU special requirements with respect to P. fragariae must be fulfilled. If the current legislation specific to P. fragariae were removed, no major consequences would be expected, unless the industry simultaneously ceased its voluntary certification activity. This is largely because of the important level of protection afforded to the industry by the widely used certification schemes for Fragaria, which significantly reduce the risks of entry, establishment, spread and impact. Certification schemes for the movement of Fragaria plants for planting offer the greatest efficiency and feasibility and the least uncertainty, especially if effective detection is incorporated into them.

The Scientific Panel on Plant Health (PLH) of the European Food Safety Authority was established in 2006 as the reference EU body for risk assessment in the plant health area in the frame of phytosanitary measures to prevent the introduction and further spread of organisms harmful (pests) to plants or plants products. Proper diagnosis and detection are critical for the categorization and assessment of pests that are or may qualify as quarantine pests, and for appropriate application of phytosanitary measures. In carrying out its responsibilities, the PLH Panel is frequently faced by the changes in taxonomy and nomenclature: these may often lead to a re-evaluation of previous pest records, concerns with published literature, and in some cases with the increased use of molecular taxonomic and identification tools. Pathogens that were previously considered strains/varieties of a single species, in some cases have now been elevated to specific status. In other cases pathogens previously recognised as species complexes have now been partitioned into named species, using molecular criteria rather than traditional methods. The problems that can arise are illustrated in this Chapter by examples representative of the main pathogen taxa.

A survey of the floors of 3001 empty sea cargo containers in storage was undertaken to estimate the quarantine risk of importing exotic insect pests into Australia, with special reference to pests of timber. More than 7400 live and dead insects were collected from 1174 containers. No live infestations of timber-feeding insects were recorded, but feeding damage detected in one floor indicates a low risk of importing colonies of timber pests in containers. The survey collection of dead insects demonstrates that containers are regularly exposed to economically important quarantinable insects, including timber pests (bostrichids, curculionids, cerambycids, siricids and termites), agricultural pests (including Adoretus sinicus, Adoretus sp., Carpophilus obsoletus and Philaenus spumarius), and nuisance pests (vespids and Solenopsis sp.). Stored product pests were found in more than 10% of containers. The assessment of pest risk associated with shipping containers is discussed in terms of the quantity and quality of opportunities for exotic insects to establish via this pathway.

Organisms generally become pests at a low rate. As a consequence of this low ‘base-rate probability’, the large majority of organisms rejected in any random sample of potential introductions would probably be harmless, despite the fairly high accuracy of some recently proposed risk assessment systems for exotic introductions. Here we distinguish between a system's accuracy (the proportion of a group of known pest species that would be correctly identified as pests) and reliability (the rate of false positives and false negatives produced once the base-rate is taken into account). We next adapt a decision theory analysis of earthquake prediction to explore when we would be best advised to ignore the recommendations of a screening system for exotic introductions. In one scenario, we show that a pest risk assessment system with an accuracy of 85% would be better ignored, unless the damage caused by introducing a pest is eight times or more that caused by not introducing a harmless organism that is potentially useful. Furthermore, because of the base-rate effect, in certain situations it may be more efficient to focus on identifying potential invaders from amongst already naturalized species than from amongst species at the importation stage.

One of the outcomes of the Uruguay Round of the General Agreement on Tariffs and Trade (GATT) was the provision for reductions in a range of agricultural trade barriers. In particular, certain types of barriers, such as tariffs, export subsidies, embargoes, import bans, quotas, supply management regimes, domestic price supports, licensing and exchange controls, were able to be dealt with by converting them into ‘tariff-equivalent’ levels of protection through a system of ‘tariffication’. The key success of this approach was that different ‘quantifiable’ trade barriers could then be compared, reduced or negotiated in a common framework of tariffs. What remained to be resolved after the Uruguay Round were a range of trade barriers that were largely non-quantifiable in terms of tariff-equivalent levels of protection. These barriers, termed ‘Technical Barriers to Trade’ (TBT), included rules and standards directed at health, safety or the environment. A key feature of TBT's, which differentiates them from quantifiable trade barriers, is that they are not specifically targeted at trade or production issues. Under GATT rules, countries are “generally allowed” to adopt health, safety or environmental policies which take precedence over other rules. The caveat to this, however, is that these policies are only allowed as long as the purpose of the policy or standard is to meet a legitimate domestic objective, and as long as domestic and foreign producers are treated in the same manner.

The Panel on Plant Health conducted a pest risk assessment for Liriomyza huidobrensis and Liriomyza trifolii in the European Union and identified and evaluated the phytosanitary measures listed in Council Directive 2000/29/EC. Entry on the principal pathways (plants for planting, cut flowers and leafy vegetables) is assessed as likely as the pests are regularly associated with the pathways at origin, survival during transport or storage is high and only partially affected by current pest management procedures, and transfer to a suitable host is likely as their hosts are so widespread. Establishment is rated as very likely because both species have established populations in most countries of the EU, with transient populations occurring outdoors in non-Mediterranean areas. Spread within the EU is considered to be likely because the pests can readily be moved with plant material. The magnitude of the potential consequences is rated as minor for both species in Mediterranean areas. In non-Mediterranean countries it is moderate for both species in protected crops but, outdoors, impacts are minor for L. huidobrensis and minimal for L. trifolii. The current regulations to prevent entry and spread were found to be only partially effective as interceptions are still being made, cut branches with foliage and leafy vegetables other than celery are excluded, and the methods for inspection and the treatments required to confirm pest free areas, places of production and consignments are not clearly specified. Removal of the legislation would have some advantages and disadvantages but may not have a major effect. The regulations could be tightened by including additional commodities, clearly prescribing the inspection procedures and the appropriate treatments to be used and combining these with other measures, e.g. screening. The application of protected zones to areas where the pests are not yet present can be applied to help prevent further spread. © European Food Safety Authority, 2012

The Norwegian Scientific Committee for Food Safety (VKM) considers that there is an overall probability that the pathogen “Candidatus Phytoplaasma mali” (AP) might spread in Norway and cause extensive economic damage to apple producers and nurseries. Stricter measures are necessary to avoid the disease to spread to districts which are not known to be contaminated, VKM concludes in a pest risk assessment commissioned by The Norwegian Food Safety Authority. The most serious effects of AP infection are secondary shoots forming “witches’ brooms” on apple trees, and crops consisting of few, small, tasteless and non-marketable fruits. Spreading AP may rapidly spread over large distances by use of infected propagation material, and locally also by insect vectors and natural root bridges. In the 2010 season there was a significant increase in the number of AP detections, mostly in the fruit-producing districts in south-western Norway. The number of farms with infected trees and the extent of infection at each farm were significantly higher than before. The disease was registered for the first time in Norway in 1996, but it may have been introduced in the 1970s. The climatic conditions are considered to be suitable for AP, and establishment is not restrained by any competitors or natural enemies. Control measures VKM states that the present control measures have not been sufficient to eradicate the disease. In the infected areas it will probably be possible to keep AP at a low level, if the current control measures are combined with permanent survey programs, testing of trees, and extensive use of disease-free planting material. These measures, however, would be at a high cost for the producers as well as the public sector., NO; en; vkm@vkm.no

VKM’s Panel on Plant Health gives the following main conclusions of the risk assessment: 1) The overall probability of entry is considered as very likely, with a low level of uncertainty. Plants for planting, scions, budwood and rootstocks are the main pathways for AP. Insect vectors are only of concern regarding local spread of AP. 2) The overall probability of establishment is considered as very likely, with a low level of uncertainty. Apple and some other species of Malus are the main hosts of the pest, and the number of host plant species is low. However, host plants are widespread and abundant in the PRA area. The vector Cacopsylla melanoneura occurs in parts of the PRA area. The climatic conditions are considered as suitable for AP because there have already been restricted outbreaks in Norway. Establishment is not restrained by competitors or natural enemies. Existing cultural or management practices are ineffective to prevent establishment. 3) AP may easily be spread by plants for planting, rootstocks, scions, budwood, and psyllid vectors. Plant materials are easily and rapidly spread within the whole PRA-area, and consequently represent a considerable risk for spread of the disease. Psyllid vectors and root bridges may be important for rapid local spread; 4) There is a high probability that AP may cause extensive economic damage in fruit orchards in the country. Apple is commonly grown in private gardens all over the southern part of Norway. In the central and northern part of Norway apple growing is restricted because of lower average temperatures. Commercial growing on a large scale is mainly restricted to some areas in the counties of Rogaland, Hordaland, Sogn og Fjordane, and Møre og Romsdal in Western Norway, and the counties of Buskerud, Telemark and Hedmark in Eastern Norway. Consequently these areas will be at most risk economically for AP to establish in Norway., NO; en; vkm@vkm.no

This paper aims to introduce an agent-based multi-criteria assessment model that support stakeholders to make multi-criteria decisions for rice pest management, this study designs agents with dynamic ability of multi-criteria decision making from information of other agents so that rice pest risk maps are built. A case study is carried out on risk assessment of brown plant hoppers in the Mekong Delta region, simulation results show that rice pest risk index aggregated from criteria and agent-based models are useful tools to support rice pest management.

In 2006, U.S. Department of Agriculture-Animal and Plant Health Inspection Service published a landmark rule providing generic radiation quarantine treatments. The rule approved radiation doses of 150 Gy for any tephritid fruit fly and 400 Gy for all other insects except the pupa and adult stages of Lepidoptera. The generic radiation treatments apply to all fresh horticultural commodities. Therefore, if a pest risk assessment demonstrates that no pupae or adult Lepidoptera are associated with a commodity, export approval can be forthcoming with no further research. Generic treatments are the culmination of decades of research but not an end point. Future research on quarantine and phytosanitary uses of radiation should focus on 1) development of specific doses for quarantine Lepidoptera not covered by the generic treatments, 2) reduction of dose levels for specific pests and commodities to shorten treatment time and minimize any deleterious effects of radiation treatment on commodity quality, 3) development of generic doses below 400 Gy for important groups of quarantine arthropods other than fruit flies, and 4) development of information on commodity tolerance and development of value-added irradiated fresh products that use generic radiation treatments. Generic treatments will facilitate safe trade between countries that have approved phytosanitary uses of radiation for fresh agricultural commodities.

CLIMEX, a climate-matching model, is described in relation to pest risk assessment. The rationale for the development Of CLIMEX is given and its various functions are illustrated with examples, using the Colorado beetle Leptinotarsa decemlineata. The beetle's climatic requirements are first inferred from its native distribution in North America. They are then used to project the relative favourableness of Europe and Asia for population growth and persistence. The role is illustrated Of CLIMEX, in association with PESKY, a prototype version of a generic expert system for pest risk assessment, in the assessment of the risk of the beetle being transferred from France to China. Finally, CLIMEX is used to search for places in North America with climates best matching that of Beijing (CN), in order to target collection of possible biocontrol agents for use against the beetle in that area, should it become established there.

The primary purpose of a national plant protection organization is to prevent the spread of quarantine pests. Such pests are characterized according to their predicted capability to be of economic importance in new areas. The determination of the potential of an exotic pest to cause crop losses is a preliminary component in a pest risk assessment (PRA) process. The initial PRA step includes two distinct ecological analyses. The first must predict the expected extent and frequency to which a new pest population will attain and/or surpass the economic injury level. This is necessary to justify the classification of an exotic pest as being of quarantine significance. Secondly, a PRA must estimate the likelihood of establishment for those quarantine pests for which an entry pathway exists. Both require that bioclimatic comparisons be made between the areas of origin and distinct target destinations. The bioclimatic methodologies of the past are currently being enhanced to specify more precisely‘quarantine pest zones of ecological equivalency’, i.e. areas within which the behavior of a specific quarantine pest can be expected to be the same. The information derived from studies that provide a basis for forecasting the behavior of indigenous pests can also be used in PRA.

Following a request from the European Commission, the EFSA Panel on Plant Health (EFSA PLH Panel) was asked to react to a document entitled “Comments on the European Union Food Safety Authority’s Pest Risk Assessment for Phyllosticta citricarpa”, authored by Hattingh et al., which was posted online in August 2014 on the website of Citrus Research International (Pty) Ltd, South Africa. Citrus black spot (CBS), caused by the fungus Phyllosticta citricarpa (McAlpine) Van der Aa, is a fruit-blemishing and leaf-spotting disease affecting citrus. P. citricarpa is not known to occur in the EU territory and is regulated as a quarantine organism in citrus (Council Directive 2000/29/EC). The Panel assessed the comments by Hattingh et al. in the light of the content of the EFSA PLH Panel Scientific Opinion on CBS and the EFSA report detailing responses to comments received during the public consultation on the draft opinion. The Panel stands by the EFSA PLH Panel Scientific Opinion on CBS and considers that the comments by Hattingh et al. have been thoroughly addressed in the EFSA report on the public consultation on the EFSA PLH Panel Scientific Opinion on CBS. A detailed point by point reply to the comments by Hattingh et al. is provided in an Appendix of this Panel statement. Since September 2014, EFSA has written to the lead author of the comments trying to engage in a scientific dialogue concerning the sources of uncertainty related to the risks posed by P. citricarpa to plant health in the EU, so as to identify ways to reduce such uncertainties (e.g. with further research and/or data exchange). The EFSA PLH Panel also remains open to such constructive dialogue in the future. © European Food Safety Authority, 2015

The EPPO Panel on Pest Risk Analysis should have an internationally agreed Pest Risk Assessment Scheme developed by the end of 1996, within the framework of the FAO standard for pest risk analysis. Such a scheme has consequences for the status of the EU and EPPO lists of quarantine pests, for the attitude and working habits of the countries in Europe and of the European Commission, for developing and other non-EU countries, and for the activities of plant protection services. A bird's eye view of these possible consequences is given.

The unmitigated pest risk potential for the importation of unprocessed logs and chips of 18 species of eucalypts (Eucalyptus amygdalina, E. cloeziana, E. delegatensis, E. diversicolor, E. dunnii, E. globulus, E. grandis, E. nitens, E. obliqua, E. ovata, E. pilularis, E. regnans, E. saligna, E. sieberi, E. viminalis, Corymbia calophylla, C. citriodora, and C. maculata) from Australia into the United States was assessed by estimating the likelihood and consequences of introduction of representative insects and pathogens of concern. Twenty-two individual pest risk assessments were prepared, fifteen dealing with insects and seven with pathogens. The selected organisms were representative examples of insects and pathogens found on foliage, on the bark, in the bark, and in the wood of eucalypts. Among the insects and pathogens assessed for logs as the commodity, high risk potentials were assigned to the following 14 organisms or groups of organisms.